Now I am older and (I hope) wiser and I have spoken with so many teachers who have told me that they started to become Math-phobic when they began doing these Math Minutes. They tell me it's not that they didn't know the answers, but that the pressure of answering the questions quickly caused their brain to freeze. This led to low scores which led to low confidence which led to more nerves which led to more low scores and so on. No wonder they ended up hating maths.
Now my anecdotal evidence is one thing but it is backed up by credible research. Jo Boaler's excellent research points out that whilst these timed tests might have been given with the best intentions, the effect is that they lead to the beginnings of Math Anxiety for a lot of students. She refers to research from Sian Bielock that shows how that the stress caused by these tests impedes students' working memory- the area of the brain where we hold our Math facts! This is backed up in the book Learning to Love Math by neurologist Judy Willis. High stress, low interest situations results in a reactive brain (fight, flight, fear) that prevents effective recall of facts.
Curiously, those who lead the Charge of the Rote Brigade will never consider this compelling evidence.
This is not to say that students shouldn't practice Math though. The more they practice the smoother the recall. However, practice doesn't make perfect: practice of the right kind makes perfect.
Good practice, for example, might involve a game situation such as The Product Game which you can see me playing with my daughter below.
Indeed there are many board games and card games which allow students to use and practise their number sense (Monopoly, Yahtzee, cribbage etc.) One which I would certainly recommend is the excellent City of Zombies in which you must use your math skills to prevent a zombie apocalypse. When I see students try games such as these, I see them more engaged, more willing to take risks, and learning more. The opposite of what I see in a Math Minute.
So, if you permit me to use some Yorkshire bluntness:
Stop pretending: Math Minutes help no-one.